Lipsett M, Hurley S, Ostro B
California Office of Environmental Health Hazard Assessment, Berkeley 94704, USA.
Environ Health Perspect. 1997 Feb;105(2):216-22. doi: 10.1289/ehp.97105216.
During the winters of 1986-1987 through 1991-1992, rainfall throughout much of Northern California was subnormal, resulting in intermittent accumulation of air pollution, much of which was attributable to residential wood combustion (RWC). This investigation examined whether there was a relationship between ambient air pollution in Santa Clara County, California and emergency room visits for asthma during the winters of 1988-1989 through 1991-1992. Emergency room (ER) records from three acute-care hospitals were abstracted to compile daily visits for asthma and a control diagnosis (gastroenteritis) for 3-month periods during each winter. Air monitoring data included daily coefficient of haze (COH) and every-other-day particulate matter with aerodynamic diameter equal to or less than 10 microns (PM10, 24-hr average), as well as hourly nitrogen dioxide and ozone concentrations. Daily COH measurements were used to predict values for missing days of PM10 to develop a complete PM10 time series. Daily data were also obtained for temperature, precipitation, and relative humidity. In time-series analyses using Poisson regression, consistent relationships were found between ER visits for asthma and PM10. Same-day nitrogen dioxide concentrations were also associated with asthma ER visits, while ozone was not. Because there was a significant interaction between PM10 and minimum temperature in this data set, estimates of relative risks (RRs) for PM10-associated asthma ER visits were temperature-dependent. A 60 micrograms/m3 change in PM10 (2-day lag) corresponded to RRs of 1.43 (95% CI = 1.18-1.69) at 20 degrees F, representing the low end of the temperature distribution, 1.27 (95% CI = 1.13-1.42) at 30 degrees F, and 1.11 (95% CI = 1.03-1.19) at 41 degrees F, the mean of the observed minimum temperature. ER visits for gastroenteritis were not significantly associated with any pollutant variable. Several sensitivity analyses, including the use of robust regressions and of nonparametric methods for fitting time trends and temperature effects in the data, supported these findings. These results demonstrate an association between ambient wintertime PM10 and exacerbations of asthma in an area where one of the principal sources of PM10 is RWC.
在1986 - 1987年冬季至1991 - 1992年冬季期间，北加利福尼亚大部分地区的降雨量低于正常水平，导致空气污染间歇性累积，其中大部分归因于居民燃木取暖（RWC）。本研究调查了1988 - 1989年冬季至1991 - 1992年冬季期间，加利福尼亚州圣克拉拉县的环境空气污染与哮喘急诊就诊之间是否存在关联。从三家急症医院的急诊室（ER）记录中提取数据，汇总每个冬季为期3个月的哮喘每日就诊情况以及对照诊断（肠胃炎）情况。空气监测数据包括每日的霾系数（COH）、每隔一天的空气动力学直径小于或等于10微米的颗粒物（PM10，24小时平均值），以及每小时的二氧化氮和臭氧浓度。使用每日COH测量值预测PM10缺失日的值，以建立完整的PM10时间序列。还获取了每日的温度、降水量和相对湿度数据。在使用泊松回归的时间序列分析中，发现哮喘急诊就诊与PM10之间存在一致的关系。当日的二氧化氮浓度也与哮喘急诊就诊相关，而臭氧则不然。由于该数据集中PM10与最低温度之间存在显著交互作用，与PM10相关的哮喘急诊就诊的相对风险（RRs）估计值取决于温度。PM10（滞后2天）每变化60微克/立方米，在20华氏度（代表温度分布的低端）时对应的RRs为1.43（95%置信区间 = 1.18 - 1.69），在30华氏度时为1.27（95%置信区间 = 1.13 - 1.42），在41华氏度（观测到的最低温度的平均值）时为1.11（95%置信区间 = 1.03 - 1.19）。肠胃炎急诊就诊与任何污染物变量均无显著关联。包括使用稳健回归以及用于拟合数据中的时间趋势和温度效应的非参数方法在内的多项敏感性分析支持了这些发现。这些结果表明，在一个PM10的主要来源之一是居民燃木取暖的地区，冬季环境中的PM10与哮喘恶化之间存在关联。
